The present inventive concept relates generally to nonvolatile memory devices. More particularly, the inventive concept relates to nonvolatile memory devices controlling a program voltage pulse.
Examples of nonvolatile memory devices include flash memory devices and variable resistance memory devices. Contemporary flash memory devices may be generally categorized as NAND flash memory or NOR flash memory. NOR flash memory has a structure in which memory cells are independently connected to a bit line and a word line. NOR flash memory is characterized by fast (random) data access speeds. In contrast, NAND flash memory requires only one contact per memory cell string because a plurality of memory cells are connected in series. NAND flash memory is characterized by very high memory cell integration density.
Flash memory like other forms of nonvolatile memory retain stored data in the absence of applied powered. Within mobile devices such as cellular phones, PDA digital cameras, portable game consoles, and MP3 players, flash memory is widely used to store programming code and payload data. Flash memory devices may also be used in home applications such as HDTVs, DVDs, routers, and GPSs.
Many conventional nonvolatile memory devices are configured to incorporate a memory cell array including multi-bit memory cells capable of storing more than one data bit per memory cell in order to further enhance data storage density. Multi-bit memory cells are commonly referred to as Multi-Level Cells (MLCs), while single-bit memory cells are referred to as Single-Level Cells (SLCs). As is well understood in the art, MLCs operate to store data using two or more threshold voltage distributions.